Flash lamp annealing (FLA) of thin silicon films can be used as a low-cost alternative to laser crystallization. Such films, for example, may be used in producing different devices, including thin film transistors (TFTs). The flash lamp pulse durations may be as short as 10 μs or as long as 10 ms.
However, FLA provides limited control over the nature and the location of the grain boundaries in the crystallized thin film. This limitation can pose problems for creating uniform transistors. FLA also may result in a material with a high volume of defects resulting from long lateral explosive crystallization. Therefore, materials produced by FLA may have lower performance levels than materials produced from other methods, including Sequential Lateral Solidification (SLS) and Excimer Laser Annealing (ELA). ELA crystallized thin films with an excimer laser. However, such laser source is not only expensive to purchase but also expensive to use, largely because of the laser tube replacements that are required. Conversely, FLA may provide uniform materials at a low cost and high-throughput, and scalable to large area thin films.
SLS and ELA crystallization techniques are limited by the length of the line beam in both applications. For example, for large area thin films, e.g., thin films having a length greater than 1.3 meters and a width greater than 1.5 (for example, Gen-5 (1.3 m×1.5 m), Gen-6 (1.5 m×1.8 m) or Gen-8 (2.2 m×2.5 m) thin film panels) the SLS or ELA line beam can not provide uniform beam properties over the entire width or length of the large area thin film. Thus, the SLS or ELA scan is performed in small sections of the film area, requiring panel movement in both the x and y directions to successfully process the film. Not only does scanning in both the x and y directions increase the duration of the process, but it also produces lesser quality films with beam edges and non-uniformities between crystallization scans, than scanning a smaller film would produce.